Formation of hRSV A matrix lattice

Based on mass spectroscopy of purified viral particles of human respiratory syncytial virus (RSV) A2, the ratio of matrix protein M to nucleocapsid protein N is ~1:1 (Radhakrishnan et al. 2010). Based on the curatorial estimation that viral genomic RNA is packaged around 209 oligomeric rings of N protein, of which 129 are N decamers (10 N subunits) and 80 are N hendecamers (11 N subunits), and taking into consideration the experimentally determined length of RSV genomic RNA (Bose et al. 2015), number of genomic RNA nucleotides bound by each N subunit (Tawar et al. 2009), and the ratio of N decamers to N hendecamers in RSV nucleocapsids (Tran et al. 2007), the total number of N proteins in a viral nucleocapsid is expected to be 2170. As M protein forms dimers, which are a prerequisite for further oligomerization during matrix lattice formation as well as formation of viral filaments and viral budding (Förster et al. 2015), we are showing that 1085 M dimers are involved in formation of the matrix lattice around the nucleocapsid.<br><br>Virion assembly occurs in cytoplasmic inclusion bodies localized in the vicinity of the plasma membrane region where virus filaments, which represent budding virions, form. Each infected cell usually contains several viral inclusion bodies of irregular shape and varying sizes (Radhakrishnan et al. 2010).<br><br>Based on cryogenic electron microscopy (cryoEM) and cryogenic electron tomography (cryoET), M protein dimers form a helical lattice that constitutes an endoskeleton under the viral envelope (Conley et al. 2022; Sibert et al. 2021).

基于对人类呼吸道合胞病毒A2型（RSV A2）纯化病毒颗粒的质谱分析，基质蛋白M与核壳蛋白N的比率为约1:1（Radhakrishnan等，2010年）。根据馆员估算，病毒基因组RNA被包裹在209个N蛋白寡聚环中，其中129个为N十聚体（10个N亚基）和80个为N十一聚体（11个N亚基），并考虑实验确定的RSV基因组RNA长度（Bose等，2015年）、每个N亚基结合的基因组RNA核苷酸数量（Tawar等，2009年）以及RSV核壳中N十聚体与N十一聚体的比率（Tran等，2007年），预计病毒核壳中的N蛋白总数为2170个。由于M蛋白形成二聚体，这是在基质晶格形成、病毒丝状体和病毒芽生过程中的进一步寡聚化以及病毒芽生的先决条件（Förster等，2015年），我们展示出1085个M二聚体参与了围绕核壳的基质晶格的形成。<br><br>病毒组装发生在位于质膜区域附近的细胞质包涵体中，病毒丝状体，即芽生病毒，在此处形成。每个感染细胞通常含有几个形状不规则、大小不一的病毒包涵体（Radhakrishnan等，2010年）。<br><br>基于冷冻电子显微镜（cryoEM）和冷冻电子断层扫描（cryoET），M蛋白二聚体形成螺旋晶格，构成病毒包膜下的内骨骼（Conley等，2022年；Sibert等，2021年）。